1. Field of the Invention
The present invention relates generally to drive control systems for construction machines of the type including a milling drum, such as for example milling machines, surface miners or stabilizer/recycler machines. An adaptive advance drive control system for such machines aids in the prevention of lurch forward events when the machine is operating in a down cut mode.
2. Description of the Prior Art
During the normal operation of a construction machine having a milling drum, it is desirable that the operator be able to maintain control over the forward or rearward motion of the machine, regardless of the operation of the milling drum. If the reaction forces exerted by the ground surface on the milling drum exceed the control forces applied to the milling drum by the weight, motive force and braking force of the construction machine, then a lurch forward or lurch backward event of the construction machine may occur. If the construction machine is operating in a down cut mode the reaction forces on the rotating milling drum may cause the construction machine to lurch forward, or if the rotating milling drum is operating in an up cut mode, the reaction forces on the milling drum may cause the construction machine to lurch back. And if the machine is in the process of being lowered too fast into the cut the reaction force on the rotating milling drum may cause the construction machine to lurch forward or backward depending on the cutting mode, i.e. at down-cut mode or up-cut mode.
Prior art systems have typically dealt with such undesirable events by detecting the event after its occurrence and then shutting down the operating systems of the machine. Examples are seen in U.S. Pat. No. 4,929,121 to Lent et al.; U.S. Pat. No. 5,318,378 to Lent; and U.S. Pat. No. 5,879,056 to Breidenbach.
There is a continuing need for improved systems for maintaining control of construction machines having milling drums, and particularly for reducing or altogether eliminating the occurrence of lurch forward or lurch backward events.